81559616 has 28 divisors (see below), whose sum is σ = 162895788. Its totient is φ = 40515072.

The previous prime is 81559613. The next prime is 81559651. The reversal of 81559616 is 61695518.

It can be written as a sum of positive squares in 2 ways, for example, as 51265600 + 30294016 = 7160^2 + 5504^2 .

It is not an unprimeable number, because it can be changed into a prime (81559613) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5990 + ... + 14106.

Almost surely, 2^81559616 is an apocalyptic number.

It is an amenable number.

81559616 is a deficient number, since it is larger than the sum of its proper divisors (81336172).

81559616 is a wasteful number, since it uses less digits than its factorization.

81559616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8286 (or 8276 counting only the distinct ones).

The product of its digits is 64800, while the sum is 41.

The square root of 81559616 is about 9031.0362639068. The cubic root of 81559616 is about 433.6690122222.

It can be divided in two parts, 8155 and 9616, that added together give a palindrome (17771).

The spelling of 81559616 in words is "eighty-one million, five hundred fifty-nine thousand, six hundred sixteen".